The proposal outlines an integrated research and career development plan for Yi-Zhou Jiang PhD to complete postdoctoral training in molecular vascular biology in the laboratory of Dr. Peter F. Davies and transition to independent research. During the K99 mentored period, I will take advanced courses in bioinformatics and epigenetics, and receive specific training in mouse genetics and management both on campus and at the Jackson Labs. Concurrently my mentor, an internal advisory committee at the University of Pennsylvania and 2 external advisors will provide one-on-one experimental training and quarterly committee review. A professional development program and individual mentoring round out the career development plan for successful transition to an independent academician during the R00 phase in preparation for R01 research. My overall research goal is to determine the role of epigenetic mechanisms in mediating endothelial phenotypes in relation to the initiation and development of atherosclerosis. I have recently discovered flow- mediated plasticity of DNA methylation in regulating endothelial gene transcription (Circ Res 2014), a newly emerging area in arterial biology and pathology (Vascul Pharmacol 2014). My review paper in Arterioscl. Thromb Vasc Biol, Endothelial epigenetics in biomechanical stress is also in press. My research proposal tests the overall hypothesis that endothelial epigenetic mechanisms sensitive to flow characteristics and hypercholesterolemia dynamically modulate endothelial phenotypes to regulate the initiation and progression of atherosclerosis. I will focus on detailed epigenetic mechanisms of the important endothelial molecules KLF4 and FOXO1 specifically linked by the SIN3A co-repressor system in a longitudinal study of hypercholesterolemia in pigs, by causality studies of SIN3A in transgenic mice, and in flow studies of human endothelial cells in vitro. Aim 1 will test the hypothesis that the multi-subunit epigenetic transcriptional co- repressor SIN3A regulates KLF4 and FOXO1 as a response to hemodynamic flow characteristics. Aim 2 will test the hypothesis that hyperlipidemia regulates transcription factors KLF4 and FOXO1 by spatio-temporal redistribution of SIN3A co-repressor complex from LXR-targeted genes to DMR-associated KLF4 and FOXO1. Thus this proposal probes epigenetic mechanisms as a common link for spatially-defined atherogenesis.